February 2014

02/12/2014

post by Andrew Freiden on 9:34am Wednesday. I grabbed some of this text from our forecast on www.nbc12.com/weather which is where our forecasts live 24/7. You can find the whole discussion there.

TIMING:1.) There will be an initial period of HEAVY SNOW on this evening over all of central Virginia. This snow may be accompanied by some heavy bands. We expect roads to become snow-covered and treacherous quickly.

2.) As warmer air noses in, we'll see a change over to FREEZING RAIN and RAIN in most of the Richmond metro area around midnight tonight. Once that transition occurs, accumulating snowfall will effectively end. Snow and sleet will continue overnight in the far northern and western counties (like Louisa and Fluvanna)

3.) Only light rain/freezing rain is in the forecast for early tomorrow morning and we may even see a brief lull in the storm.

4.) ADDITIONAL Snow (not included in the snow forecast below) is possible Tomorrow afternoon and evening. This might produce an extra inch or two of snow.

IMPACTS:- SLICK ROADS: Roads will become snow covered this evening. A changeover to freezing rain will add a layer of ice on top of snow, will make conditions even more slick. *IF YOU DON'T HAVE TO TRAVEL TONIGHT, DON'T.* - POWER OUTAGES: We are forecasting generally .10 inch or less of ice BUT Brunswick, Greensville, and Emporia may see up to .25 inch. Ice accumulation on trees and power lines can lead to power outages.

No major changes to our snowfall totals map since last night. We still anticipate that snow will move in by mid-afternoon (4 - 7 PM metro Richmond) and will continue into the overnight hours.

- In the PINK ZONE (Charlottesville, western Louisa, Fluvanna, and Buckingham counties), you'll find the highest totals because we anticipate mainly SNOW through the duration of the event in these areas.

- In the YELLOW ZONE (Fredericksburg, through Louisa, Powhatan, and western Amelia counties), we are forecasting 6-10 inches of snowfall, STARTING as HEAVY SNOW, and then changing to SLEET.

- In the WHITE ZONE (Tappahannock, Richmond, Petersburg, through South Hill), we are forecasting 3-6 inches of snowfall, STARTING as HEAVY SNOW, then transitioning to FREEZING RAIN.

- In the BLUE ZONE (Williamsburg, Wakefield, through Sussez, and Greensville counties), we are forecasting 1-3 inches of snowfall, STARTING as HEAVY SNOW, with a QUICK transition to rain.

The main hazards with this event remain slick roads and the potential for power outages.

This forecast panel is what we think will happen a little after midnight Wednesday following the initial few hours of heavy snow Wednesday evening. A probable changeover to freezing rain and cold rain along the I-95 and I-85 corridor will bring a sudden end to accumulating snow in those areas. This includes much of metro Richmond. We'll see if this trend continues to be indicated in future model runs, but it makes sense given the weather set-up we're dealing with, as the cold air source, high pressure east of New England, will be moving farther away and warmer air comes in aloft.
There will consequently be a very sharp gradient of snow totals over central Virginia.
Andrew will have updates in the AM!
-Jim Duncan

The bigger slice I added in yellow makes me nervous. We're going to be watching a layer of warm air that could cut into this total by changing it over to freezing rain or sleet for a while tomorrow night.

Our fluffy January snow forecasts were all about "how much snow?"This forecast is a lot about "how long will it be snow (vs. freezing rain or sleet)?"

02/10/2014

This is our snowcast map for the upcoming storm as of Monday evening update time. Note the zone of 4-8" predicted for central Va and metro RVA area due to greater liklihood of a change to freezing rain from snow than points farther west, where precip will fall mostly as snow, with subsequent higher totals predicted.
This remains a tricky set-up, with a warm nose of air aloft pushing west Wednesday night forcing a changeover along the I-95 corridor. Any slight shift in this, either farther west or east, will mean shifts in the snow "zones" the same directions.
-Jim D.

Good morning... a quick update at 11:25. As we get closer, the trend looks SNOWIER with less sleet/freezing rain. Also, onset of snow on Wednesday keeps getting pushed back. Ros is working up new maps/forecasts now.

Our past two storms were fluffy snow with the only forecast challenges being HOW MUCH we'd get. Now, appears like we are back to normal with all precipitation types on the table.

The now-famous European Model has been persistent on this storm for days now, so we watch each run of the model (twice daily) for subtle hints and changes.... This morning, I notice a couple of quick things to mention.

1) Snow start time (wednesday afternoon) is trending later Now, it looks like the start time would be afternoon in RVA versus the morning.

2) Storm looks plenty strong but a smidge closer to the coast, which would mean a quicker changeover to rain in Richmond (Wednesday night) after a period of heavy snow.

Here's a look at the ONSET of the storm, which will probably be snow.

Then transition through precipitation types would probably happen Wednesday night.

Here's the Wednesday NIGHT forecast:

See how warm air "eats" away at the storm from the SE? a tough forecast going forward with potential big snow toward the mountains with mainly rain at the coast. Richmond: stuck in between.

For planning purposes: both Wednesday evening and Thursday morning's commutes could be BAD.

02/09/2014

LATE SUNDAY NIGHT WINTER STORM UPDATE: Well, new computer data coming into the weather office tonight not prompting any major changes to the forecast as of yet....one thing that has changed is that the onset of the snow may be delayed a bit from what I had described earlier this evening. Based on this new data, the snow is likely to hold off until late Wednesday morning, and it's possible we don't see the first flakes falling until sometime Wednesday afternoon.

So ultimately, what is the key to how much snow we can expect to fall over Central Virginia? Well, one problem we have to face if you're a snow lover is the fact that the cold ridge of high pressure centered to our north will be sliding off the coast. What then becomes critical is the ultimate track of the area of low pressure....is it just offshore? right along the shoreline? or does the low track more inland? This will be crucial in determining how far west and northwest the rain/snow line will move into interior Virginia.....the farther offshore that the low tracks, the more snow we are likely to see here in the heart of Central Virginia. I still think several inches of snow are possible before any changeover would occur, but a shift in track of the low further inland would end up bringing us more rain in Richmond than anything else.

I know there is a hunger to know exactly "how much" you might expect to see in your neighborhood right now...maybe you live in Matoaca, or Blackstone, Reedville, Short Pump, Midlothian or Ashland etc....I am confident we will get a more clear picture of the storm track over the next 24-36 hours and be able to give you a more specific "how much" to expect in your area. Stay tuned for more updates, and as always, thanks for watching! Have a great night! -ROS RUNNER. You can fine me on Facebook at facebook.com/Ros Runner NBC12 Weather.